Add Sign up functionality paid plan

Hello!

I am currently developing a project for my bachelor's degree, utilizing Okta functionalities. Now I have a free account and in my project the Sign up functionality does not work (the Sign up button appears, but with no action). I understood that this feature is not available for free accounts. Could you kindly advise me on which paid plan would be best to purchase in order to have that feature? I need a paid plan only for enabling this feature, because my actual account functionalities are enough for me.

Thank you!